Violet-black azo dye and process of making same.



OTTO ERNST AND KARL SCHIRMAUHER, OF HflOHST-ON-THE-MAIN, GER- MANY, ASSIGNORS TO THE FARBWERKE BRENING, OF SAME PLACE.

VlULE'l' fiLfilClfi AZU DYE AND PROCESS OF MAKING SAME.

formingpart of Letters Patent No. 667,935, dated February 12, 1901.

Application filed May 23, 1900. Serial No. 17,627. ($peoimens.)

T0 aZZ whom it may concern:

Be it known that we, OTTO ERNST, Ph. D., and KARL Scrnrnmonnn, Ph. 1)., subjects of the Emperor of Germany, residing at lldchstolrtlie-Main, Germany, have invented certain new and useful improvements in the Man ufac- Lure of Violet-Black Azo Dyestuffs for 7001, of which the following is a specification.

The black azc dyestuffs for W001 hitherto and now on the market are all disazo dyestuffs, which, though inferior in their property of dyeing evenly, are generally employed in wool-dyeing on account of their comparative cheapness and some advantages in their properties of fastness.

Several methods have become known of late by which black dyes may be obtained on wool with evenly-dyeing monoazo dyestuffs-as, for instance, that described in the German Patent No. 90,770. The monoazo dyestuffs produced for this purpose, however, could not compete with the disazo blacks for wool obtained partly from the cheapest material in the coal-tar industry. Ne have found that from diazotized 6 11itroQ-amido-l-phen01-4:- sulfonic acid, on theone hand, and beta-naphthol,on the other hand, a monoazo body may be obtained which directly dyes wool deep violet and which on treatment with chromium compounds may be transformed into a black dye of excellent properties. The tinctorial power is considerable. The fastness to water, acid, alkali, light, rubbing, and sulfur is excellent. The fastness to milling and shrinking is perfect, and the properties of dyeing evenly are very remarkable, for even inferior material of loose wool is dyed evenly. The valuable properties of the beta-naphthol dyestuff, especially its deep-violet shade, could not be foreseen. In fact, the sulfonic acids of betanaphthol, combined with diazotized 6-nitro-2- amido-phenol-a-sulfonic acid, yield inferior products, though when combined with diazo compounds in general they produce bluer shades than beta-naphthol itself does. Even the substitution of an isomeric nitroamidophenolsulfonic acid for 6-nitro-2-amidophenol-a-sulfonic acid leads to little practical result.

The manufacture of the new dyestuff is as follows: 3.8% kilos of sodium nitroamidophenolsulfonate are dissolved in one hundred liters of water, to which are added 3.30 liters of hydrochloric acid of 30 Baum, and the solution is diazotized at 10 to centigrade. The yellow-colored diazo solution is run into a cold solution of 0.70 kilo of caustic soda,

kilos of soda-ash, and 2.20 kilos of betanaphthol in thirty liters of water. The formation of the dyestul'f takes place at once and the liquid becomes blue violet. The dyestuff separates for the most part as a greenish-colored precipitate. The liquid is heated to about centigrade and stirred at this temperatu re for some hours. On addition of some salt the small portion of the dyestuff which is in solution is also separated.

hen in a dry state, the dyestuif is a brown powder of bronze luster, soluble in Water with a violet color, little changed by ammonia. Alcohol dissolves only small quantities of the dyestuff yielding, a blue-violet solution.

The solution of the dyestuflin concentrated sulfuric acid is bluish red. When water is added, the dyestu'tl' separates as a brick-red precipitate.

Having now described our invention, What We claim is l. The herein described process for the manufacture of a vi0let-black dyestuif for wool, which consists in combining the diazo compound of 6-nitro-2amido-phenol-4-sulfonic acid with beta-naphthol to a monoazo dyestuff, substantially as set forth.

2. The herein-described new black azo dyestuff, which, when in a dry state, is a brown powder of bronze luster, soluble in Water with a violet color, little changed by ammonia, alcohol dissolves only small quantities of the dyestulf yielding a blue-violet solution; in concentrated sulfuric acid the solution of the dyestuff is bluish red, when Water is added the dyestuff separates as a brick-red precipitate, substantially as set forth.

In testimony that we claim the foregoing as our invention we have signed our names in presence of two subscribing Witnesses.

OTTO ERNST.

KARL SCI'IIRMACHER.

Witnesses:

HEINRICH HAHN, ALFRED BRISBOIS.

, VORMALS MEISTER, LUOIUS & 

